1. Technical Field
The invention relate to a thin film transistor, a thin film transistor panel and a fabricating method thereof.
2. Discussion of the Related Art
A flat panel display, such as a liquid crystal display (“LCD”) or an organic light emitting display (“OLED”), typically includes a plurality of pixels. The pixels are arranged in a matrix on an insulating substrate such as glass or plastic. Each pixel includes pairs of field generating electrodes and an electro-optical active layer, such as liquid crystal molecules or a light emitting layer, interposed between each pair of field generating electrodes.
A pixel electrode, which is one of the electrodes in the pair of field generating electrodes, can be connected to a switching element that transmits electrical signals to the pixel electrode. The electro-optical active layer converts the electrical signal into an optical signal to display images.
A plurality of thin film transistors (“TFT”) is typically used for the switching elements in the flat panel display. Each TFT typically includes a gate electrode, which receives a switching signal, a source electrode, which receives a data signal, and a drain electrode, which outputs the data signal to a pixel electrode. The TFT includes a semiconductor layer disposed between the source electrode and the drain electrode. Typically, an amorphous silicon layer has been used as the semiconductor layer. Recently, a TFT with high quality such as high driving speed is required for realizing a display device featuring a large size and highly resolution. Thus, an oxide semiconductor layer may be used instead of the amorphous silicon layer. Typically, a plurality of layers are deposited and then patterned, e.g., by photolithography processes using masks, thereby fabricating the TFT. In the event a TFT is fabricated using an oxide semiconductor layer, the oxide semiconductor layer can be damaged by a subsequent patterning process, thereby resulting in TFT degradation.